Electrical receptacles or outlets as well as electrical switches are electrically connected to current-carrying electrical conductors of copper wires covered with insulation. The procedure to electrically connect the electrical conductors to electrical contact members of the receptacles or switches involves the following: strip the insulation to expose wire ends of the copper wires, form the wire ends into hooks, place the hooks under heads and around the shafts of screws of the contact members, and tighten the screws thereby securing the copper wires on the contact members and effecting electrical connections therewith.
Care must be exercised in each of the above steps to insure an effective electrical connection. The insulation must be removed so as not to nick or cut the copper wires, because nicking or cutting the copper wires weakens them and also creates a local spot of increased electrical resistance due to copper material being removed which will result in a local hot spot as electrical current flows through the copper wires. The hooks must be large enough to fit around the screw shafts but small enough to be engaged by the screw heads upon tightening of the screws. None of the insulation must be disposed between the screw heads and the contact members. If insulation is present in the electrical connections, the connecting force applied to the copper wires will be decreased thereby increasing the electrical resistance of the electrical connections. The screws must be tight in order to provide optimum electrical connections; however, overtightening the screws will strip the threads of the screws or the threaded holes of the contact members, thereby resulting in poor electrical connections. Increases in electrical resistance caused by poor electrical connections described above result in increases in temperature during current flow which could also result in ignition of flammable material in close proximity.